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It might help to clarify the research question a bit to the list.  Someone
might be able to direct you to a more efficient path to your project's
objective that wouldn't involve tussling with -stset- over multiple episodes
of mastitis during successive periods of lacation, when it's a one-time
culling that you're ultimately interested in.

Joseph Coveney

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st: probable error stset

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From: "Lucy Shum" <[email protected]>
Subject: st: probable error stset
Date: Wed, 17 Jan 2007 12:07:42 +1100

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Hi,

I'm tackling a probable error issue which I have partially solved.  Issue is
that Stata views certain variables as identical over the same patient, with
multiple events recorded. Anybody knows of a command to "turn off" the
detection of such events?

I attach here one of the -stset- output.

stset dim, id(id) failure(censor) exit(time .)

                id:  id
     failure event:  censor != 0 & censor < .
obs. time interval:  (dim[_n-1], dim]
 exit on or before:  time .

------------------------------------------------------------------------------
     7033  total obs.
       26  multiple records at same instant                   PROBABLE ERROR
           (dim[_n-1]==dim)
------------------------------------------------------------------------------
     7007  obs. remaining, representing
     4226  subjects
     1982  failures in multiple failure-per-subject data
  1222502  total analysis time at risk, at risk from t =         0
                             earliest observed entry t =         0
                                  last observed exit t =       785

Cheers


Lucy Shum


Lucy Shum
Bovine Resident
University of Sydney
University Veterinary Centre Camden
Tel: +61-2-46550777
Fax: +61-2-46551212

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st: stsplit

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From: "Lucy Shum" <[email protected]>
Subject: st: stsplit
Date: Wed, 17 Jan 2007 14:15:52 +1100

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Hi,

I've got a dataset with multiple records per animal, multiple events per
record.

Here it is:

list

     +----------------------------------------------------------+
     | id   xmast   mast   censor   dim   dimm1   dimm2   dimm3 |
     |----------------------------------------------------------|
  1. |  1       0      0        0   280       0       0       0 |
  2. |  1       3      1        0   300     150     170     250 |
  3. |  1       1      1        1   290     200       0       0 |
  4. |  2       1      1        0   450     100       0       0 |
  5. |  4       1      1        0   300     135       0       0 |
     |----------------------------------------------------------|
  6. |  4       2      1        0   210     200     208       0 |
  7. |  5       3      1        0   350      31      50     200 |
  8. |  5       2      1        0   324     280     300       0 |
  9. |  5       0      0        1   299       0       0       0 |
     +----------------------------------------------------------+

I need to examine the data with "xmast" as a time-dependent covariate since
the hazard of culling should logically alter with every additional episode
of mastitis in cows.

"dim" is the total number of days the cow is present in the milking herd.
"dimm1" is the day when the first disease event occurs, "dimm2" is the when
the second episode happens etc. Total episodes are defined by "xmast".

I can't specify to Stata when to split the data because these are biological
data. Further, I already KNOW when each event occurs. But how do I put it
all together, hopefully, using -stsplit-  to split the records where
"xmast>1"  and the corresponding dimm1/2 or 3 will be recorded?

Help is very appreciated!!

Lucy

Lucy Shum
Bovine Resident
University of Sydney
University Veterinary Centre Camden
Tel: +61-2-46550777
Fax: +61-2-46551212

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st: stsplit

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From: "Lucy Shum" <[email protected]>
Subject: st: stsplit
Date: Thu, 18 Jan 2007 09:29:20 +1100

--------------------------------------------------------------------------------

Hi,

How do I go about -stsplit- a record which represents one animal, with
multiple events recorded within this line? The time when these events
occurred are not in any logical order and hence I don't think I can command
the stsplit with -stsplit newvar, at(0, 320) per se.

Here is one example:



How could I split the xmast event (number of episodes) into 2 rows? The
corresponding time is in dimm1, dimm2.

Input is much appreciated.

Lucy

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